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way that is more streamlined than what we’ve been doing in the past,” Tung says. “It’s not something that we’re ready to roll out in fullness right now.”

While this statement leaves more questions than answers about the initiative, Tung does say that his company has been in talks with regulators in the U.S. and overseas about the effort. This interest is indicative of how truly different Concert’s deuterium-modified compounds are from traditional experimental drugs. Typically, initial human testing is primarily done to gauge the safety of compounds, which likely have never been tested in people before. Tung explains that it’s almost a given that Concert’s drugs are as safe as the originals, because deuterium-modification of approved drugs doesn’t change the ways the drugs work in a biochemical sense.

Deuterium forms stronger bonds with other atoms in a drug compound than hydrogen does. In theory, the stronger bonds keep more of a deuterium-modified compound intact—as it travels through the digestive tract, the liver, and into the bloodstream—than the original drug. This means deuterium drugs could be less toxic in the liver. Patients might also be able to take lower doses of drugs with deuterium modification, because more of the compounds reach the bloodstream intact than the originals. Concert has also shown that deuterium-modification lowers the risk of adverse drug interactions in patients.

Concert’s leading commercial contender is its HIV drug called CTP-518, which is the top drug candidate in its Glaxo collaboration. The startup is doing multiple Phase I studies with the compound, which is a deuterium-modified version of Bristol-Myers Squibb’s HIV protease inhibitor, atazanavir. Deuterium could make the drug potent in the bloodstream for longer than the original drug, possibly enabling patients to do without Abbott Laboratories’s booster drug, ritonavir. (Read Luke’s story that focuses on the HIV program.)

Glaxo has the option to take over development of Concert’s lead HIV drug after the startup completes the initial human studies, which would bring in more revenue for Concert. Concert has already gained $16.7 million in equity investments and $30.3 million in payments from Glaxo in the overall partnership. The Phase I studies of CTP-518 are slated to conclude in 2011, and Glaxo’s decision on whether to take the next step with the program promises to be a major moment for Concert. (The firms are also collaborating on an anti-inflammation drug for people with chronic kidney failure.)

Concert, which has raised a total of $142.5 million from investors and Glaxo’s payments, has enough cash to operate for at least another two years, Tung says. This cash cushion puts the firm in a position to continue advancing its pipeline without immediately requiring more capital from a round of venture financing or another Big Pharma collaboration.

“Right now we’re taking a relatively low-key approach to business development,” Tung says. “We’re keeping in touch, meeting with people, and having them informed about our technology. But we’re letting ourselves mature our pipeline before we go to make a push for partnering.”

Ultimately, the company can get better terms in a collaboration involving clinical assets as opposed to one with compounds that haven’t advanced into clinical trials. So a key for Concert, as Tung says, is to get more of its drugs into the clinical setting to generate human data. We’ll see how successful the company is in its new initiative to streamline this process.